As flow cytometer systems become smaller and more portable, the sheath fluid containers and the waste fluid containers are becoming correspondingly smaller and more portable. As a result, portable flow cytometer systems may exhaust the supply of sheath fluid or overfill the waste container during the course of an experiment. While refilling or replacing the sheath fluid container and emptying the waste container takes a nominal amount of time and effort, the user must continuously suspend the experiment to ensure that the sheath fluid is not entirely depleted and that the waste container is not overfilled. Should the sheath container become empty, data sampled from or around the time when the sheath fluid ran out may be compromised. Accordingly, a user will typically have to provide a new sample material and run new experiments to ensure the accuracy of the data. Similarly, should the waste container overflow, the user will undoubtedly have to suspend the experiment in order to clean and sterilize the area. As the samples analyzed by flow cytometers vary from relatively benign to much less so, the overflow of the waste container can cause serious delays and perhaps hazardous conditions.
Thus, there is a need for improved flow cytometer flow system that is adapted to determine a volume of the sheath fluid and the waste fluid during operation. This invention provides such an improved and useful flow cytometer system.